Application Update: Industrial Robot Control

Integrated safety controls are part of Fujitsu motherboards and software for the Kuka KR C4 robot control, based on Microsoft Windows and Ethernet, reducing the robot’s hardware by 35% and plugs and cables by half, and saving energy.

04/28/2011

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After Kuka’s 1996 launch of the world’s first full Microsoft Windows-based industrial robotic controls, the robot manufacturer replaced many hardware functions in the KR C4 system with intelligent software, including, for the first time, integrated safety and energy savings. The new system requires 35% less hardware and 50% fewer plug connections and cables compared to its predecessor.

Highly available mainboards

In choosing the mainboards [motherboards], Kuka continues to use Fujitsu Technology Solutions, board supplier for KR C2 controls since 2005, chosen after several months of testing for quality, availability, and durability.

“Our control systems have to stand 24/7 operation at an ambient temperature of up to 45 °C [113 °F],” explains Heinrich Munz, senior software developer at Kuka.

“Like Kuka, Fujitsu’s development department and production are located in Augsburg. This makes it easy to be in regular contact with our motherboard manufacturer when preparing an upgrade of our control,” Munz noted.

The prior version worked with a single-core processor. For the new generation of controls, a multicore processor provides more computing power and independent operating cores that use software to replace external safety control, automation control, and other hardware.

For Kuka, the mainboard D2608-K for the new robot control was derived from the Fujitsu standard product D2608-A, already used in several thousand Fujitsu Celsius workstations. “Kuka profits from the mass production of the base version” that has a “high degree of product maturity. Due to a high output volume, cost can be kept down, and availability of the materials has also been secured in the long run,” explained Peter Hoser, director OEM sales at Fujitsu Technology Solutions in Augsburg, responsible for industrial mainboard distribution.

The D2608-A is a workstation mainboard based on the Intel X3 Express chip set for Intel Core2 Duo and Intel Core2 Quad processors. Six-layer construction ensures highest signal quality and reliability in operation, Hoser said. At the beginning of Kuka’s new robot control design phase, Fujitsu initiated necessary board adjustments, such as voltage monitoring, system management microcontroller, and custom Kuka functions implemented in the BIOS.

Embedded safety PLC

Other mainboard modifications accommodate the KR C4 safety control for the emergency stop (implemented as safety PLC), communicating using “Safety over Ethernet.” During the KR C4’s three-year development time, safety functions were integrated into dual software created by two compilers on two CPU cores with TÜV documentation and certification.

Hoser said the additional effort translated into “technology leadership for Kuka, regarding the realization of a safe, cost-efficient robot control, which nearly revolutionized the interaction of humans and robot.”

With Kuka Safe Handling technology, a human operator can enter the workspace of the robot and work with it hand-in-hand, without switching to “Test mode” during production.

Multicore technology enables the implementation of an embedded safety PLC, according to safety requirement IEC 61508 SIL2, on two channels on the two independent processor cores. Higher processor computing power allows an integrated 8 kHz controller for reliable position control. Ethernet telegrams can be communicated within 125 microseconds.

Fujitsu also developed a durable Dual Gigabit Ethernet card for Kuka. The card and D2608-K’s onboard Gigabit Ethernet controller serve as interfaces between the robot’s control computer and the outside world.

Green automation

Ethernet enables other functions, including energy savings. Even when production halts on weekends, robots are seldom shut down, because a complete reboot of the production equipment on Monday mornings takes too long, resulting in very high and unnecessary energy consumption. With the “wake on LAN” function of the Ethernet controller, all systems can receive a sleep-mode telegram from a central hub on Friday evenings. A centrally controlled Monday morning wake-up call puts all controls into the same state they were left in on Friday, saving energy.

Servo controllers

Both generations of the Kuka robot also use Lenze servo expertise. According to Lenze, the new Kuka Power Pack for the KR C4 integrates a power supply module and up to two servo controllers. Lenze and Kuka designed the Kuka Servo Pack for the other axes with the same maximum power output, combining three servo controllers in one unit, with peak currents of 64 A per axis. The new control cabinet (shown above) holds up to three units, powering eight axes, Lenze said.